035-14370-000
650.75-N4U
Unitary Products Group
35
MAINTENANCE
Air Filters
The filters must be checked periodically for dirt accumulation.
Dirty filters greatly restrict the flow of air and may cause dam-
age to the system.
Clean the filters at least every three months. On new con-
struction, check the filters every week for the first four weeks.
Inspect the filters every three weeks after that, especially if
the system is running constantly.
All filters used with the furnace are the high-velocity, clean-
able type. Clean these filters by washing in warm water.
Make sure to shake all the water out of the filter and have it
reasonably dry before installing it in the furnace. When
replacing filters, be sure to use the same size and type as
originally supplied.
Filter Removal - Upflow Models
The ends of the retainer are attached to the rear panel in two
metal loops. Refer to Table 42 on page 35. The ends must be
squeezed together to free them from the loops. The retainer
may then be moved to the new location and the ends inserted
in the loops on the rear panel at the new location. Loops are
provided for retainer location to accommodate filter applica-
tion on the bottom or either side of the furnace.
To remove a filter from the bottom location, push the closed
end of the filter retainer to the left until it clears the lip on the
front of the furnace base, which acts as a catch for the
retainer. When the retainer is clear of the flange, it will pivot in
the loops.
Swing the retainer toward the center of the furnace. This will
expose the filter to allow removal. To reinstall the filter, simply
reverse this procedure.
Filter Removal - Downflow Models
1.
Turn off electrical power supply to the furnace at discon-
nect switch. Remove access doors.
2.
Filters are installed in the plenum area above the blower
assembly. Filters rest against the side of the plenum wall
and are supported in the middle by a frame. Lift filter
slightly to dislodge and remove for service.
3.
Remove the filter and follow the cleaning instructions
above. DO NOT remove the filter stiffener rods, if pro-
FIGURE 41 : FURNACE CONTROL EVENT SCHEDULE
FIGURE 42 : UPFLOW FILTER RETAINER
